Methods, arrangements, and structures related to the technical field mentioned above and having a function and being of a character which fulfils the requirements as proposed are known in the prior art in a plurality of different embodiments.
Thus it can be mentioned that harvesting arrangements or equipments of the relevant type which support its drive motor unit and to which unit a guide bar arrangement is easily applicable and easily separable over a clamping and coordinating arrangement are adapted to extend with their endless saw chain from a drive disc allotted to the drive motor unit, said drive disc ordinarily being shaped as a toothwheel, and the saw chain tracks along and around the guide bar to form the guide bar arrangement.
The drive motor unit comprises i.a. a means extending (or loosening) a saw chain towards the guide bar for enabling fastening (and loosening) the drive motor unit to and from the guide bar and in a clamping condition means to allow a limited displacement movement of the guide bar arrangement with regard to the drive motor unit, normally for extending the saw chain.
Motor saws and motor saw arrangements of the type belonging thereto are as a rule driven by a hydraulic circuit placed under an hydraulic overpressure and which over controllable hydraulic valves can feed a drive motor driven by hydraulic pressure within the drive motor unit with a controllable hydraulic flow and the hydraulic pressure which it requires for generating the necessary amount of power so that such motor saw may be driven under more or less maximized conditions.
Such maximized conditions are well developed in the field of tree and timber harvesting or logging, wherein the conditions refer i.a. to letting the saw chain operate in a maximized translation movement, such as 40 meters per second, and controlling the engagement pressure between the cutting teeth of the saw chain and a wooden material intended for being cut, primarily in the form of logs and timber, and wherein an adapted engagement pressure and a cutting capacity can be controlled by the momentary number of revolutions of the drive motor and its disc and choosing the diameter and number of teeth for the toothwheel driven by the drive motor unit, wherein said toothwheel is to be driven by a hydraulic motor, and selecting the volume of the driving motor and hence its number of revolutions dependent on the chosen maximized translation movement.
As an example of the background of technology and the technical field to which the present invention refers with regard to motor saws in general and particularly to motor saw arrangements or units may be mentioned the presence of a clamping and for coordinating arrangement between a drive motor unit and a guide bar arrangement adaptable to the drive motor unit and in which a unit and/or an arrangement are attached but easily removable from each other via said clamping and coordinating arrangement with its clamping means.
As an example of the background of technology and the technical field to which the present invention refers may be mentioned a guide bar arrangement having a specific shape of its inner end portion of the guide bar, which is shown and described in European Patent Application EP 0 993 767 B1.
Here a motor saw arrangement shown and described being designed with the inner first end portion or area of said guide bar (according to the following FIG. 12) is not only provided with a centrally located slot (40), which extends partly along the guide bar, corresponding to known technology (according to FIG. 2), but is also provided with two side-disposed guiding holes or slots for adapting a chosen extension of the saw chain along the guide bar over an arrangement extending the saw chain and its guide bar by on the one hand moving these slots towards the edge surface of the guide bar and furthermore shaping the center lines of these slots so that they connect to the direction of a central middle line of the slots and with slots opening symmetrically oriented to said edge portion.
A support plate and a clamping plate are here shaped to cover solely part of the central slot.
To the earlier standpoint of technology belong also the measures that are required to rapidly be able to inactivate the clamping arrangement and without a saw chain to loosen and turn around or replace one guide bar by another alternatively in connection therewith to initially replace a utilized saw chain and/or a guide bar by a new such one.
Different clamping arrangements have also been proposed, which have been formed such, that replacing of a guide bar arrangement and/or a guide bar can be carried out with simple means and having loose and separatable components, which might be lost in difficult terrain and/or snow during a replacement sequence.
Various clamping means have also been proposed, which in inactivable position will offer a guide bar movement in the direction from the drive motor unit, the chassis thereof and along a plane of the guide bar and its support plate.
Manual actuation of the tightening or clamping arrangements to inactivable or alternative activable positions have also been proposed, where the clamping arrangement can serve as a means extending the saw chain towards and along its guide bar.
Patent Publication U.S. Pat. No. 5,709,254 A according to FIGS. 4 and 5 shows a chassis related arrangement with a support plate (106) and a clamping plate (104) as well as clamping and/or loosening means (a bolted joint).
It is specifically indicated that the guide bar (100) and particularly two blocks (104, 106) allotted to the illustrated arrangement can be displaced in active position for extending and/or slackening the saw chain over means intended for this, for example letting the saw chain extend along said guide bar.
The principle of this arrangement can be considered to imply that when the arrangement is disposed in activable position the end portion of the guide bar facing the chassis and attached by a bolted joint and being disposed in an inactive position, such as for replacement of the guide bar, there is a coordinated arrangement requiring that the clamping plate (104) be removed and displaced as a unit entirely from the chassis so that the guide bar is made free in such manner.
Thus, the clamping plate (104) must during its inactive position be entirely removed from the chassis as an independent unit.
In the inactivated position, i.e. a position in which the guide bar and saw chain have been removed from their attached position in the motor unit or chassis and where the guide bar with mounted and stretched saw chain is to be introduced into the arrangement to an activating and tight-holding position, at least the clamping plate (104) belonging to the arrangement and its means or bolt joint will exist in individual loose parts that may easily go lost.
Patent Publication U.S. Pat. No. 3,870,125 A shows and describes a clamping arrangement that in a position illustrated in FIG. 7 requires two bolts (28, 30) secured to the chassis, said bolts being adapted to support said guide bar by a within said end area formed slot (20) and where said clamping plate (42) is to clamp said guide bar and its mounted saw chain by using two nuts (34).
In said inactivated position such a coordinating arrangement requires that said clamping plate (42) and at least two nuts (34) are kept as separated easily lost parts.
Patent Publication GB 539956A shows and describes a clamping arrangement in the form of a coordinating arrangement having a clamping plate and a support plate, where screws (18) are adapted to be formed to fit key holes (17) in order to secure the inner area of the guide bar (8).
In an inactivated position this coordinating arrangement requires that at least the clamping plate is formed as a separate part.
Patent publication U.S. Pat. No. 3,870,125 A shows and describes an arrangement having two separated clamping plates (7, 8), where one can be considered as a support plate and the other as a clamping plate with an intermediate guide bar (3) and in activated position the two plates (7, 8) and the guide bar (3) are clamped by nuts (10).
In inactivated position such a coordinating arrangement requires that at least one plate (8) and in any case two nuts (10) are in the form of loose, easily lost, parts.